The process of splicing a sheet (or "web") of material to another sheet of material is a common operation in a number of industries. In particular, in many paper industries, it is necessary to splice two webs of paper together in order to maintain a single unbroken web. This splicing operation is necessary for efficient operations downstream of the splicing equipment, which are fed with a steady and uninterrupted stream of web material. To maximize the efficiency of downstream operations, it is desirable to feed the web in a fast and steady manner without stopping or considerably changing the web speed. Conventional web splicing equipment is relatively inefficient, typically requiring the operator to stop the web or to significantly reduce web speed to splice the two ends of material.
In an effort to compensate for these inefficiencies, several conventional web splicing systems employ a variety of methods and assemblies to keep the web speed fed to downstream systems as fast and as continuous as possible. For example, as web material from an almost-expended roll (the "running roll") is fed at normal operating speed, certain systems will gradually bring a fresh roll of material (the "ready roll") up to the same speed, at which time the two webs are brought together and spliced. Such a system is disclosed in U.S. Pat. No. 3,252,671 issued to Phillips, Jr. et al. A drawback of such a system is that a large amount of web material which is fed through the splicer prior to the time the web speeds are matched is wasted during each splicing operation.
Other conventional web splicing systems perform their splicing operations by bringing the web from the ready roll up to speed very quickly. Such a system is disclosed in U.S. Pat. No. 5,252,170 issued to Schaupp. By bringing the ready roll web up to speed quickly, the material waste just described is avoided. However, systems which operate in this manner limit the types of web material which can be spliced. Many types of web material including, without limitation, toilet paper and tissue paper, are relatively low weight, low strength, and/or high stretch materials. Splicing operations performed by high-acceleration splicers on such materials perform poorly, and often result in ruptured webs or weak splices which are unable to withstand the rigors of downstream web operations.
Another disadvantage of many conventional web splicing systems (such as the one just described) is the manner in which the web splice is made. In particular, webs are often spliced by taping the ends of the two webs together. Especially in systems where the spliced area experiences a high amount of tension and/or in which the splicer does not provide a good speed match between the webs being spliced, a taped splice is often necessary. However, taped splices are undesirable because the spliced section of the web must eventually be removed from the web (for example, prior to the packaging of the final product) or the end products having the taped splice are must be discarded. Either method of discarding the tape-spliced product section represents a waste of product. Furthermore, many tape splice systems require the operator to manually tape the two webs together. Not only does this typically require a section of both webs to be stationary for a period of time, but this is a labor-intensive inefficiency which is realized every time a splice is made.
As yet another example of how conventional web splicing systems attempt to feed downstream operations with a fast and continuous stream of web material through web splicing operations, certain systems use a bank of festoons or idler rolls immediately downstream of the splicer system. One such system is disclosed in U.S. Pat. No. 5,360,502 issued to Andersson. The festoon or idler rolls in such systems are adjusted to accommodate a significant amount of web material during normal web operations. When a web splicing operation is performed, the festoons or idler rolls move to release the web material wound therein. This process permits the web speed at the splice position (upstream of the festoons or idler rolls) to be temporarily reduced or stopped while the speed of the web material downstream of the festoons or idler rolls (i.e., for downstream machinery), is kept constant or only slightly reduced. When the splicing operation is complete, the web material passing the splicing area is brought back up to the speed of the web downstream of the festoons or idler rolls. A significant disadvantage of the web splicing system just described is the need for one or more banks of festoons or idler rolls and control elements and assemblies required for their operation. These components increase cost, maintenance, and floorspace requirements. Furthermore, it is of critical importance that a constant tension is maintained on the web throughout each operation performed upon the web. If constant tension is not maintained, web wrinkling and (in severe cases) web rupture can occur. Each festoon roll or idler roll added to a system creates web wrinkling and tensioning problems. Systems which attempt to address these problems by employing driven rolls in the bank of idler or festoon rolls inevitably introduce more expense, complexity, and maintenance costs into the system.
In view of the disadvantages of conventional web splicing systems noted above, there exists a need for a web splicing apparatus and method which can splice light weight, low strength, and high stretch web material without reducing the downstream speed of the web, which does not require additional elements or subsystems (e.g. a bank of festoon or idler rolls) to accommodate excess web material downstream of the splicer, and which can quickly and accurately accelerate a web up to the speed of a running web without the need for a taped splice and without the danger of web rupture during the splicing operation. The present invention provides such an apparatus and method.